The overall objective of this research proposal is to assess the DNA repair capability of lung and trachea of hamsters after administration of polycyclic hydrocarbons. In this regard, the extent of alkylated bases of DNA was determined as a function of time after administration of either 3-methylcholanthrene or benzo(a)pyrene. Persistent binding of 3-methylcholanthrene to susceptible mouse lung DNA was observed.